In a S4C series, the naturalist Iolo Williams burrows into the hidden lives of some of the most well-known and best-loved mammals in the UK countryside. We know a lot about how rabbits, badgers, and even the water vole behave above the ground but as they are nocturnal and live mainly underground, it’s often difficult to get a complete picture of their habits. In this series, using carefully designed artificial burrows, we observe how these animals live and behave underground.